Exam: Work, Power, and Machines
Give two examples of kinetic energy becoming potential energy.

a)

b)

Give two examples of potential energy becoming kinetic energy.
a)

b)

What is the formula for calculating the efficiency of a machine?
 
 
 

Why do you always multiply the efficiency by 100?
 
 
 

If a container weighs 58 N, then it should take 580 J of work to move it 10 m up a ramp.  However, it actually takes 640 J of energy to move it due to friction.  What is the efficiency of this system?
 
 

Define and give an example in parenthesis:
open system
 

closed system
 

What is a perpetual motion machine?
 
 

Why is it impossible to build a perpetual motion machine?
 


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